JPH0658289B2 - Optical fiber measurement method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring transmission characteristics and optical characteristics of an optical fiber.

2. Description of the Related Art Transmission characteristics and optical characteristics to be measured of an optical fiber include transmission loss, transmission band, numerical aperture, cutoff wavelength of second mode, and mode field diameter of fundamental mode. In order to measure these, conventionally, the measurement light is made incident on one end of the optical fiber, and the light emitted from the other end is received, and the intensity (spatial spread) and the intensity (spectrum) depending on the intensity thereof are measured. Is to be weighed. Alternatively,
Light is incident from one end of the optical fiber, and the backscattered light from each part of the optical fiber is extracted from this incident side terminal and measured. The backscatter method is also used for measurement.

For example, when measuring the transmission loss, as shown in FIG. 6, the beam emitted from the light source 1 is focused by the lens 6 and is incident on one end of the optical fiber 3 to be measured. This light propagates through the fiber 3 and is emitted from the other end, and this emitted light is incident on the light receiver 5 via the lens 7. The output signal of the light receiver 5 is amplified by the amplifier 8 if necessary, and then sent to the voltmeter 9 to display an amount proportional to the amount of received light.

By the way, normally, after spinning, the optical fibers are wound one by one on an individual drum, and then, depending on the structure of the optical fiber cable, the optical fibers are covered one by one or a plurality of optical fibers are collected. , Coated with resin and made into a tape,
It may be ribboned or twisted together as a unit with a round cross section.

Problems to be Solved by the Invention The conventional measuring method as described above has a disadvantage that it takes a lot of time for preparation in addition to the original measuring time, and therefore the whole measuring time becomes long. That is,
In order to perform measurement with good reproducibility, always under constant conditions,
Light must be incident on the optical fiber to be measured, or the light emitted from the optical fiber to be measured must be extracted. Therefore, it is only necessary to accurately irradiate the end face of the optical fiber to be measured with the incident light beam spot at the incident end. This is because the end surface of the optical fiber to be measured is cut perpendicularly to the fiber axis and is flat, and dust and the like must not adhere. Therefore, most of the time required for measurement is not the original measurement time of light, but the time required for preparation such as alignment of the input and output axes of light and shaping of the fiber end face becomes dominant.

In particular, in the case of a single-fiber optical fiber in which each optical fiber is individually coated, it is necessary to process the end face of the optical fiber for each optical fiber to adjust the light input / output. Is remarkable.

The present invention provides an optical fiber measuring method that facilitates the work even when measuring the single-fiber optical fiber coated one by one, shortens the overall measuring time, and easily improves the accuracy. The purpose is to provide.

Means for Solving Problems According to the present invention, light is incident on a terminal of an optical fiber to be measured, light propagated in the optical fiber is emitted from the terminal, and the emitted light is measured. In the method, the vicinity of the ends of the plurality of optical fibers to be measured are aligned substantially parallel and integrated, and the end faces of the integrated plurality of optical fibers to be measured are collectively molded, and one end is connected to the light source. A plurality of existing ones of the other end of the optical fiber for incidence, which are integrated in parallel with each other in the vicinity of the other end, are respectively connected to the ends of the plurality of optical fibers under test. Has become.

Operation Since the ends of multiple optical fibers to be measured are integrated, the work of removing their coatings and shaping the end faces can be performed at once. In addition, since the terminal portion of the incident optical fiber is similarly integrated, the connection with the incident optical fiber can be performed simultaneously for a plurality of fibers. You can do it all at once. In this way, handling and work for measuring a plurality of optical fibers to be measured are facilitated. Therefore, the total measurement time can be shortened and the measurement accuracy can be easily improved.

Practical Example First, as shown in FIG. 1, both ends 31 of a plurality of single-core optical fibers 3 to be measured are aligned and arranged in parallel. Generally, each of the optical fibers 3 to be measured is measured in order to determine whether or not they have good characteristics that can be formed into a cable. Often, so drum 3
Roll out from 0 to a suitable length and align both ends as above. In this case, the optical fiber 3 is not exposed by the glass, but is covered by a so-called primary coat or secondary coat.

Next, the terminals 31 are integrated in a state where they are aligned in parallel. As an integration method, the resin is hardened with a thermoplastic, thermosetting, or ultraviolet curable resin, or with a low-melting point metal. Alternatively, the terminals 31 aligned in parallel may be sandwiched between the two tapes and bonded together. In this embodiment, as shown in FIG. 2, the ultraviolet cross-linking resin 32 is used for integration. The bundle of the optical fibers 3 is pulled upward while injecting the ultraviolet crosslinking resin from the nozzle 35 into the portion of the guide 34, and at this time, the ultraviolet light from the ultraviolet lamp 37 is guided by the ultraviolet guide fiber bundle 36 and the resin 3
2 is irradiated to cure the resin 32 and integrate it to form a tape locally. In this case, the length of the integrated optical fiber is generally about 200 mm to 1 m, though it depends on the item to be measured and the fiber length required for the subsequent processing.

In this way, the terminals 31 of the plurality of optical fibers 3 to be measured are integrated with the resin 32 in a tape shape, and the subsequent handling becomes extremely easy. Therefore, a plurality of these integrated optical fibers 3 are cut flat at a time,
Perform end face shaping collectively. The state after being cut in this way is shown in FIG.

Next, the coating of the end portion of each optical fiber 3 is removed, and the fourth
The fiber core wire 33 is exposed as shown in the figure. Since this coating removal work is integrated with the resin 32,
It becomes possible to carry out collectively for a plurality of optical fibers 3.

On the other hand, as shown in FIG. 1, on the incident side, a plurality of optical fibers 2 connected to the light source 1 are integrated at the terminal 21 into a tape shape as described above. Also on the emission side, the terminals 41 of the plurality of optical fibers 4 connected to the light receiver 5 are similarly integrated into a tape shape. Therefore, since the input and the output of light to and from the plurality of optical fibers 3 to be measured are performed from the tape-shaped one to the tape-shaped one, it becomes substantially inconvenient to align the optical axes one by one, and as a whole, Optical axis alignment is extremely easy. Further, in this case, if necessary, the optical fibers can be easily connected to each other by fusion splicing, whereby connection can be made with low loss, and reliable and highly accurate measurement can be guaranteed.

Since the terminals 31 are integrated as described above, it is only necessary to cut the end faces of the plurality of fibers 3 once.
Also, the work of removing the coating of a plurality of fibers 3 is required only once,
Moreover, since it is easy to align the incoming and outgoing optical axes,
For example, when the insertion loss of a single-fiber optical fiber is measured individually, it takes about 50 minutes to measure five fibers.
It can be done in 20 minutes, and the effect of shortening the entire measurement time is remarkable.

FIG. 5 shows a second embodiment. In this embodiment, the backscatter method is adopted as the measuring method of the optical fiber.
One end 31 of each of the plurality of single-core optical fibers 3 to be measured is aligned and arranged in parallel. The other terminal has an open end. And near one terminal arranged in parallel,
It is the same as in the above-mentioned embodiment that it is solidified with resin or the like to be integrated, and is cut flatly all at once and the coating is removed. Further, the terminals 21 of the plurality of optical fibers 2 for entering and exiting are also integrated into a tape shape as in the above. A light source and a light receiver are included at one end of each of the plurality of optical fibers 2, and light is incident on one end of the optical fiber 2 while receiving backscattered light emitted from each end of the optical fiber 2 from each end. The measuring instruments 11 for measuring the respective values are connected to each other. A plurality of optical fibers 2 and a plurality of measured optical fibers 3
Are connected so that the terminals 21 and 31 formed in a tape shape are butted against each other, and the light incident from the measuring instrument 11 is propagated in the optical fiber 2 and the optical fiber 3, and at each part thereof. Scattered light and reflected light travel in opposite directions and return to the incident end side again. This light is received by the light receiver of the measuring device 11, and the states of scattered light and reflected light at each part thereof are shown by the display device 12.

Also in the case of such a backscatter method, since the terminal 31 is integrated, it is easy to handle, the work is simple, and the entire measurement time is shortened.

EFFECTS OF THE INVENTION According to the present invention, even when measuring a single-fiber optical fiber coated one by one, shaping (cutting) of a single surface of a plurality of fibers and coating removal work can be performed collectively. It can be done easily. In addition, since the terminal portion of the incident optical fiber is similarly integrated, the connection with the incident optical fiber can be performed simultaneously for a plurality of fibers. You can do it all at once. Since the work is facilitated in this way, the overall measurement time is shortened. It is also easy to improve the measurement accuracy.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of the present invention, FIGS. 2, 3, and 4 are perspective views showing an end portion of an optical fiber in each step, and FIG. 5 is a schematic view of another embodiment. FIG. 6 is a schematic view of a conventional example. 1 ... Light source, 2 ... Incident optical fiber 3 ... Measured optical fiber, 4 ... Emitting optical fiber 5 ... Photoreceiver, 32 ... Resin 34 ... Guide, 35 ... Nozzle 36 ... Fiber Bundle, 37 ... UV lamp 6, 7 ... Lens, 8 ... Amplifier 9 ... Voltmeter, 11 ... Measuring device 12 ... Display device

Claims (3)

[Claims] 1. An optical fiber measuring method in which light is incident on a terminal of an optical fiber to be measured, light propagated in the optical fiber is emitted from the terminal, and the emitted light is measured. The steps of aligning the ends of the optical fibers substantially parallel to each other and integrating them, the step of collectively shaping the end faces of these integrated multiple optical fibers to be measured, and the multiple ends of which are connected to the light source Of the other end of the optical fiber for incidence, which are integrated in parallel with each other in the vicinity of the other end, are connected to the ends of the plurality of optical fibers to be measured. Measuring method of optical fiber. 2. A terminal connected to a plurality of integrated incident optical fibers is one terminal of the measured optical fiber, and the light emitted from the other terminal is propagated through the optical fiber. Claim 1 characterized by measuring
The optical fiber measurement method described in the item. 3. A terminal connected to a plurality of integrated incident optical fibers is one terminal of the optical fiber to be measured, and is emitted from this one terminal. The method for measuring an optical fiber according to claim 1, wherein the backscattered light is taken out from the incident side terminal and measured.